Resettable plunger switch assembly



April 13, 1965 J. s. LoRY r-:TAL

a RESETTABLE PLUNGER SWITCH ASSEMBLY Filed April 3, 1965 United States Patent O RESETTABLE PLUNGER SWITCH ASSEMBLY John S. Lory, Bloomfield, and Harry Ashworth, Thompsonville, Conn., and Robert D. Chierico, Flushing, N.Y.,

assignors to HI-G Incorporated, Windsor Locks, Conn.,

a corporation of Connecticut Filed Apr. 3, 1963, Ser. No. 270,447 7 Claims. (Cl. 200-87) This invention relates to electrical switches and more particularly to resettable electric switches of the plunger type.

It is a principal aim of the present invention to provide a new and improved switch of the type described that is economically constructed for one-time operation with use, for example, as a replacement for the conventional squib actuated switch used in projectiles, missiles and other aerospace vehicles, and which provides a high degree of reliability within adverse environments of dust, temperature, moisture and extreme conditions of vibration, shock and G loading. The usual one-time operable switch, of which the squib actuated switch is an example, cannot be operationally tested before use, with the consequence that complete operational reliability is never ensured. Therefore, an adjunct of the principal aim of the present invention is to provide an economical switch useful for one-time operation and capable of being tested under operational conditions for ensuring maximum reliability and thereafter reset for actual operational use.

It is another aim of the present invention to provide a switch of the type described incorporating an improved assembly of stationary and movable electrical contacts that may be suitably arranged for simultaneously making or breaking a num-ber of electrical circuits and wherein the movable contacts are shiftable with a minimum force for making or breaking contact, but nevertheless have a large effective contact area ensuring lo-w electrical resistance through the switch.

It is a further aim of the present invention to provide a new and improved switch of the type described that is electrically acitvated from an incipient preset position, which thereafter remains in the active position until reset and which has an arrangement of parts of compact size and low weight for facile assembly and installation.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth, and the scope of the application of ywhich will be indicated in the appended claims.

In the drawing:

FIG. l is a longitudinal section view partly broken away of a switch constructed in accordance with the present invention;

FIG. 2 is a transverse section view of the switch taken along line 2-2 of FlG. l;

FIG. 3 is an isometric partly exploded view of a portion of the switch; and

FIG. 4 is an enlargement of a portion of FIG. 3.

Referring now to the drawings in detail, and in particular to FIG. l which shows an embodiment of a switch of the present invention two and one-half times its preferred size, an elongated switch casing or support body lil, preferably of aluminum and substantially square in the transverse plane, has a longitudinally extending cavity 12 adjacent one end thereof, and varying diameter coaxial bores, generally denoted by the numerals 14 and 16, extending longitudinally from the cavity 12 to the ends of the casing.

Upon reference to FIG. 2, the cavity 12 is substantially rectangular in the transverse plane and opens into 3,178,533 Patented Apr. 13, 1965 "ice a casing recess 17 defined in part by a peripheral lip 1S about .the cavity. A molded insert or housing 20 having molded therewith a plurality of longitudinally spaced pairs of electrical contacts 22 is snugly received within the casing cavity, and is accurately positioned therein by the engaging peripheral shoulders 23 and 24 provided -by an outer flange 26 of the insert and a corresponding recess 28 in the casing. The insert is securely retained within the casing by crimping the lip 18 over a peripheral charnfered edge 3) of the insert.

The insert 20 has a central bore 32 coaxial with the casing boresv 14 and 16, and the pairs of contacts 22 have arcuately shaped contact portions 34 with partially cylindrical contact faces 36 concentric with the bore 32 and spaced inwardly thereof. Terminals 3S of the contacts 22 are apertured adjacent the ends thereof for making electrical connections.

A movable contact support or spool 4l) is loosely mounted in the bore 32 for reciprocable movement from the 4position shown in FIG. l with its inner end 42 in engagement with the casing shoulder 44 to a position where its opposite end 46 engages the shoulder 48 of the casing. rIhe cylindrically shaped spool has ve axially spaced lands defining four annuli receiving a corresponding number of resilient movable contacts 50 (only one being shown) that are spaced with respect to the spacing of the pairs of stationary contacts 22 to make electrical contact with the 4faces 36 thereof when the spool moves to the left from the position shown in FIG. 1. Where desirable, of course, one or more of the cooperating movable and stationary contacts could be relatively spaced to provide for breaking electrical contact with leftward spool movement.

Each movable contact 50 is formed Vfrom resilient sheet material and includes a central cylindrical portion 52 rotatably supported on the reduced porti-ons 513 of the spool 40 and retained thereon by a wire 57 (FIG. 4) and a plurality of radially and axially extending iingers 54 formed to provide outwardly convex .arcuate contact portions 55 adapted for resilient engagement with the bore 3-2 and With the faces 36 of the stationary contacts 22. inasmuch as the faces 36 are positioned inwardly of the bore 32, contact pressure between the arcuate contact portions 55 and the stationary contacts is assured, and inasmuch as the contact portions 5S are arcurately shaped and the spool 40 is loosely received within the bore 32, the spool is shiftable with a minimum force. Additionally, the contacts provide a large contact area giving low electrical resistance notwithstanding any relative misalignment of the stationary and movable contacts.

The spool 40 is operated by a plunger or actuator 64 having an enlarged flange portion 62 slidably mounted for rectilinear movement in a bore portion 66 of the bore 14. The plunger 64 has an enlarged head 68 received within a T-shaped slot 70 in the spool 40 enabling the plunger to be assembled with the spool concurrent with the assembly of the insert 20 in the cavity 12 and for thereafter retaining the plunger and spool against relative longitudinal movement.

A one-way latch, generally designated by the numeral 72, normally holds the plunger and movable contact subassembly against movement to the left (as seen in FIG. l) by the engagement of three ball bearing followers 74 equally spaced about the elongated rod 76 of the plunger. The ball bearings are assembled in three radially extending apertures in a carrier sleeve 78 that is slidably mounted on the plunger rod 76 intermediate the plunger and a camming bushing 80. The bushing 80 is radially spaced from the ball and ball carrier sleeve and is press-tit within a bore portion 82 of the bore 14 against the casing shoulder 84. The bushing 89 has centrally therein a frustoconical or axially tapering inwardly facing camming surface 86 engageable by the ball bearing followers '74 to cam or wedge them inwardly for locking the plunger 64. A bushing cap 88 is press-fit within the bushing at the outer axial end of the camming surface 86 and a cornpression coil spring 9() is compressed between the cap 88 and a radial shoulder 92 of the carrier sleeve 78 to bias the carrier sleeve and the ball bearings to the left (as seen in FIG. l) for providing the one-way latching of the plunger 64.

An electromagnetic actuator, generally denoted by the numeral 96, is snugly received in an enlarged bore prtion 98 of the bore 14 and includes a central cylindrical core 106, electrical insulating sleeves 102 and 106, an energizing coil or solenoid 104 and a magnetic end piece 107, all disposed securely within a magnetic sleeve 108. The actuator 96 is rigidly retained within the casing 1t) through the engagement of the sleeve 108 with a shoulder 110 of the casing and by crimping a peripheral lip 111 formed on the end of the casing over a beveled peripheral edge of a cap 112. The cap 112 engages an insulator bushing 114 bearing against the sleeve 108 and forms with the bushing 114 an enclosed cavity 116 into which the solenoid coil leads 118 extend for electrical connection with a pair of spaced terminals 120 integrally molded with the cap 112.

An armature plate 124 is press-fit on the carrier sleeve 7S and is biased against a casing shoulder 126 formed between the bores 98 and 82 by a compression coil spring 128 to assist in maintaining the balls 74 in latching engagement with the plunger 64 in opposition to any G force loading on the armature and carrier sleeve. The armature plate 124 is moved to the right (as seen in FiG. l) upon energization of the solenoid 104 to move the balls 74 from the camming surface 86 for releasing the plunger 64. Upon release 'of the plunger, a cornpression coil spring 1.3i) positioned between the bushing tl and the flange 62 of the plunger moves the movable contact subassembly to the left into engagement with the casing shoulder 48 thereby completing an electrical circuit between the pairs of terminals 3S. After deenergization of the solenoid 184, the spool 4t) is retained in the active position by the spring 150, but may lthereafter .be reset to the right (as seen in FIG. 1) as with a tool 1nserted in the bore 16, with the one-way latch 72 automatically retaining the plunger in its reset portion for subsequent activation.

It can be readily seen that the present invention provides a highly compact and electromagnetically operated switch that is operable with minimum power and which is economically constructed for one-time use and yet subject to testing for ensuring reliable operationand therefore useful as a replacement for the conventional squib actuated switch now widely used in aerospace applications. Additionally, the switch of the present invention provides a compact arrangement of parts that. are reliable under adverse environments of temperature, vibration and shock oi' G loading and which is not subject to defective operation due to stray magnetic fields or, as the bore portion 16 can be conveniently plugged after testing, tine foreign matter or moisture.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

We claim:

l. A switch assembly comprising an electrical switch having a pair of cooperating electrical contacts, a longitudinally movable plunger operatively connected to one of the electrical contacts for actuating the switch, a first camming element having a longitudinally tapered camming surface facing the plunger, a second element intermediate the camming element and plunger having an opening therein, a locking member within said opening engageable with the caniming surface and plunger for locking the plunger against movement in one longitudinal direction, biasing means urging the plunger in said one longitudinal direction and urging one of said elements in an axial direction camming the locking member and locking the plunger, and selectively operable means moving said one element in the opposite axial direction for releasing the plunger and actuating the switch.

2. A switch assembly comprising an electrical switch having a pair of cooperating electrical contacts, a longitudinally movable plunger operatively connected to one of the electrical contacts for actuating the switch, a camming element having a frustoconical camming surface coaxial with and facing the plunger, a sleeve element intermediate the camming element and plunger having a plurality of angularly spaced radially extending openings, locking balls within said openings engageable with the camming surface and plunger for locking the plunger against movement in one longitudinal direction, biasing means urging the plunger in said one longitudinal direction and urging one of said elements in an axial direction camtming the balls and locking the plunger, and selectively operable means moving said one element in the opposite axial direction for releasing the plunger and actuating the switch.

3. A switch assembly comprising a casing having an elongated bore therein, an electrical switch mounted within the casing having a pair of cooperating electrical contacts, a plunger mounted for longitudinal movement within said bore and connected to one of the electrical contacts for actuating the switch, a camming element in the casing bore having a frustoconical camming surface coaxial with and facing the plunger, a sleeve element intermediate the camming element and plunger having a plurality of angularly spaced radially extending openings, locking balls within said openings engageable with the camming surface and plunger for locking the plunger against movement in one longitudinal direction, spring means within .the casing bore urging the plunger in said one longitudinal direction and urging one of said elements in an axial direction camming the balls and locking the plunger, and electromagnetic means within the casing bore upon energization moving said one element in an opposite axail direction for releasing the plunger and actuating the switch.

4. A switch assembly comprising an electrical switch having a pair of cooperating electrical contacts, a longitudinally movable plunger operatively connected to one of the electrical contacts for actuating the switch, a sleeve element slidably mounted on the plunger having a plurality of radially extending openings angularly space thereabout, a camming element having an inwardly facing frustoconical cumming surface coaxial with the sleeve and plunger, locking balls within the sleeve openings engageable with the camming surface and plunger for locking the plunger against movement in one longitudinal direction, coil spring means urging the plunger in said one longitudinal direction and urging the sleeve element in an axial direction camming the balls and locking the plunger, and electromagnetic means upon energization moving the sleeve element in the opposite axial direction for releasing the plunger and actuating the switch.

5. A switch assembly comprising an electrical switch having a pair of cooperating stationary contacts, said stationary contacts having partially cylindrical opposed coaxial contact faces, an axially shiftable member between said contact faces, and a movable contact having a cylindrical portion rotatably mounted on said shiftable member and a plurality of radially and axially extending resilient fingers contoured to provide outwardly convex electrical contact portions adapted for engagement with said contact faces; a longitudinally movable plunger operatively connected to the shiftable member for actuating the switch; a plunger latch including a camming element having a longitudinally extending camming surface spaced ent/seas radially from the axis of movement or the plunger, a sleeve element intermediate the camming element and plunger having a radially extending opening therein, and a locking ball Within said opening engageable with the camming surface and plunger for locking the plunger against movement in one longitudinal direction; biasing means urging the plunger in said one longitudinal direction and urging one of said elements in an axial direction camming the balls and locking the plunger, and selectively operable latch releasing means moving said one element in the opposite axial direction for releasing the plunger and actuating the switch. I

6. A switch assembly comprising an electrical switch having a plurality of longitudinally spaced pairs ot stationary contact elements, said pairs of stationary contact elements having partially cylindrical opposed coaxial contact lfaces, a spool member mounted for axial movement between said contact faces, and .a plurality of axially spaced movable contacts each having a cylindrical portion rotatably mounted on the spool member and at least four substantially equally angular spaced and radially and axially extending resilient fingers contoured to provide outwardly convex contact portions adapted for engagement with said contact faces, a plunger connected to the spool member and longitudinally movable for actuating the switch, spring means biasing the plunger in one longitudinal direction, spring-operated latch means locking the plunger against movement in said one longitudinal direction and selectively operable means for releasing the latch to actuate the switch.

7. A switch assembly comprising a casing having an elongated bore extending between two ends thereof and a cavity communicating with said bore; an electrical switch mounted Within the casing cavity lhaving a plurality of longitudinally spaced pairs of stationary contacts, said pairs of stationary contacts having partially cylindrical opposed contact faces coaxial with said casing bore,

a spool member mounted for axial movement between said con-tact faces, and a plurality of movable contact elements each having a cylindrical portion rotatably mounted on the spool member and a plurality of radially and axially extending resilient lingers contoured to pro vide outwardly convex contact portions adapted for selective engagement with said contact faces; a plunger connected to the spool element and mounted for longitudinal movement within the casing bore, a camming element mounted within the casing bore having an axially extending inwardly facing frustoconical camming surface, an intermediate sleeve element slidably mounted on the plunger having vthree angularly spaced radially extending openings, locking balls Within said openings engageable with the plunger and camming surface -for locking the plunger against movement in one longitudinal direction, coil spring means Within the casing bore urging the plunger in said one longitudinal direction and urging one of said elements in an axial direction camming the balls and locking the plunver, and electromagnetic means mounted within tbe casing bore including an armature connected to said one element, said electromagnetic means upon energization moving said one element in the opposite axial direction for releasing the plunger and actuating the switch.

References Cited bythe Examiner UNITED STATES PATENTS l,()52,595 2/13 Lanphier 200-l1l 1,277,576 9/18 Hart ZOU-111 1,617,862 2/27 Pistor ZOO-16 2,386,162 i0/ 45 Hetheri-ngton 200-77 2,521,561 9/60 Batcheller 200-16 2,999,912 9/61 Kincaid et al. 20G-82 BERNARD A. GTLHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. A SWITCH ASSEMBLY COMPRISING AN ELECTRICAL SWITCH HAVING A PAIR OF COOPERATING ELECTRICAL CONTACTS, A LONGITUDINALLY MOVABLE PLUNGER OPERATIVELY CONNECTED TO ONE OF THE ELECTRICAL CONTACTS FOR ACTUATING THE SWITCH, A FIRST CAMMING ELEMENT HAVING A LONGITUDINALLY TAPERED CAMMING SURFACE FACING THE PLUNGER, A SECOND ELEMENT INTERMEDIATE THE CAMMING ELEMENT AND PLUNGER HAVING AN OPENING THEREIN, A LOCKING MEMBER WITHIN SAID OPENING ENGAGEABLE WITH THE CAMMING SURFACE AND PLUNGER FOR LOCKING THE PLUNGER AGAINST MOVEMENT IN ONE LONGITUDINAL DIRECTION, BIASING MEANS URGING THE PLUNGER IN SAID ONE LONGITUDINAL DIRECTION AND URGING ONE OF SAID ELEMENTS IN AN AXIAL DIRECTION CAMMING THE LOCKING MEMBER AND LOCKING THE PLUNGER, AND SELECTIVELY OPERABLE MEANS MOVING SAID ONE ELEMENT IN THE OPPOSITE AXIAL DIRECTION FOR RELEASING THE PLUNGER AND ACTUATING THE SWITCH. 